1. Field of the Invention
The present invention relates to a decentralized arbitration device for several processing units of a multiprocessor system.
2. Description of the Prior Art
From the article on pages 154 to 158 of the April 1978 number of the review "Computer Design" an arbitration process and an arbitration device are known for a multiprocessor system comprising several identical processing units all connected to the same bus. This known arbitrator, of a synchronous type, allows a rotating priority to be established between the different processing units so that none of them monopolizes the bus, and so that the processing carried out by the multiprocessor system is the speediest possible. The known arbitrator comprises essentially a read-only memory (ROM) in which all the possible configurations of reservation requests for the bus and the corresponding states are programmed.
This known device requires a large number of connecting wires between the arbitrating device and the different processing units, which may be troublesome when the number of processing units is high.
In addition, the size of the ROM used in the known arbitrator depends on the number of processing units cooperating therewith. If the number of processing units is not very high, the capacity of the ROM required for constructing the arbitrator is correspondingly low, and the arbitrator is then inexpensive and easy to construct. On the other hand, if the number of processing units is high, several high-capacity memories must be used and the construction of the arbitrator becomes complex and costly.
The present invention has as its object a decentralized arbitration device not presenting the disadvantages of the known device, which device is easy to construct and inexpensive.